Process for vulcanizing rubber at a low temperature

ABSTRACT

A process for vulcanizing a rubber base comprising at least one halogen-containing amorphous polymer at a low temperature ranging from 5° to 85° C., which comprises carrying out the vulcanization in the presence of 0.01 to 20 parts by weight of an organic hydroperoxide and/or ketone peroxide per 100 parts by weight of the rubber base. 
     In the above process, at least one member selected from the group consisting of (I) the oxides of metals, such as zinc, lead, chromium, cobalt, nickel, magnesium, manganese, copper and iron, or the metallic salts of said metals with aliphatic or cycloaliphatic carboxylic acid having 8 to 24 carbon atoms; (II) methacrylic esters; (III) maleimides; and (IV) oximes, may be used as a vulcanization activator or a vulcanization accelerator in an amount of 0.01 to 20 parts by weight per 100 parts by weight of the rubber base.

This is a division of copending application Ser. No. 188,613 filed Sept. 19, 1980, now U.S. Pat. No. 4,310,443 which in turn is a division of application Ser. No. 33,696 filed Apr. 26, 1979, now U.S. Pat. No. 4,248,987, which in turn is a division of application Ser. No. 814,918 filed July 12, 1977, now U.S. Pat. No. 4,166,892, which in turn is a continuation of Ser. No. 655,547 filed Feb. 5, 1976, now abandoned, which in turn is a continuation of Ser. No. 429,588 filed Jan. 2, 1974, now abandoned.

The present invention relates to a process for vulcanizing at least one halogen-containing amorphous polymer at a low temperature. More particularly, it pertains to a process for vulcanizing at least one halogen-containing amorphous polymer at a low temperature, in which an organic hydroperoxide and/or ketone peroxide as a vulcanizing agent is used alone or in combination with a specific vulcanization activator or accelerator to achieve the vulcanization at a temperature as low as from 5° to 85° C.

As the known literature references concerning a low temperature vulcanization process using an organic hydroperoxide as a vulcanizing agent, there are Japanese Patent Publication Nos. 19,930/67 and 16,584/70. These relate to amorphous copolymers consisting of ethylene, alpha-olefin and cyclic or acyclic polyene having non-conjugated double bond. There is found no literature concerning the halogen-containing amorphous polymers which are the object of the present invention.

At present, halogen-containing amorphous polymers are, in many cases, used in adhesives, paints and sealants. It is greatly significant that a low temperature vulcanization be applicable to these uses. In order to attain this object, therefore, the present inventors have long done extensive research on the low temperature vulcanization of halogen-containing amorphous polymers to achieve this invention. This invention is characterized by using an organic hydroperoxide or ketone peroxide as a vulcanizing agent.

An object of the present invention is to provide a process for vulcanizing halogen-containing amorphous polymers at a low temperature.

Another object of the present invention is to provide a process for vulcanizing at a low temperature halogen-containing amorphous polymers, which process is applicable to adhesives, paints and sealants.

A further object of the present invention is to provide a process for vulcanizing halogen-containing amorphous polymers at a low temperature, in which an organic hydroperoxide or ketone peroxide is used as a vulcanizing agent.

A still further object of the present invention is to provide a process for vulcanizing halogen-containing amorphous polymers at a low temperature, in which an organic hydroperoxide or ketone peroxide as a vulcanizing agent is used together with a vulcanization activator or a vulcanization accelerator.

The other objects and advantages of the present invention will become clear from the following description.

According to the present invention, there is provided a process for vulcanizing a rubber base comprising at least one amorphous polymer at a low temperature ranging from 5° to 85° C., which comprises carrying out the vulcanization in the presence of 0.01 to 20 parts by weight of an organic hydroperoxide and/or ketone peroxide per 100 parts by weight of the rubber base, and, if necessary, in the presence of 0.01 to 20 parts by weight of at least one vulcanization activator or accelerator selected from the group consisting of (I) metal oxides or metallic salts of aliphatic or cycloaliphatic carboxylic acids having 8 to 24 carbon atoms, (II) methacrylates, (III) maleimides and (IV) oximes, per 100 parts by weight of the rubber base.

The halogen-containing amorphous polymers in the present invention include, for example, chloroprene rubber, chlorinated polyethylene, chlorosulfonated polyethylene and chlorinated ethylene-propylene-diene rubber, and the halogens include chlorine and bromine. Chlorine is the most popular and important.

The rubber base in the present invention includes halogen-containing amorphous polymers alone, mixtures thereof and mixtures of halogen-containing amorphous polymer and halogen-free amorphous polymers. More particularly, it includes not only a mixture obtained by mixing the halogen-containing amorphous polymer with the halogen-free amorphous polymer for the purpose of enhancing the weather resistance and heat resistance and reducing the cost of the halogen-containing amorphous polymer but also a mixture obtained by mixing the halogen-free amorphous polymers with the halogen-containing amorphous polymer for the purpose of enhancing the tackiness and adhesiveness of the halogen-free amorphous polymer or imparting flame-proof property to the halogen-free amorphous polymer. In other words, it is indispensable for the rubber base described herein to comprise at least one halogen-containing amorphous polymer. The halogen-free amorphous polymers include, for example, styrene-butadiene rubber, ethylene-propylenediene rubber and natural rubber. Further, the halogen-free amorphous polymers used for the present invention include low molecular weight amorphous copolymers such as low molecular weight ethylene-propylene rubber, too.

The organic hydroperoxides and ketone peroxides used in the present invention include, for example, alpha-cumyl hydroperoxide, tertiary butyl hydroperoxide, p-menthane hydroperoxide, m,p-diisopropylbenzene-monohydroperoxide, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, acetylacetone peroxide, and the like.

Another great feature of the present invention is that at least one compound belonging to the following groups may be used as a vulcanization activator or a vulcanization accelerator to adjust the vulcanization velocity:

(I) The oxides of metals such as zinc, lead, chromium, cobalt, nickel, magnesium, manganese, copper and iron; and the metallic salts of these metals with aliphatic or cycloaliphatic carboxylic acids having 8 to 24 carbon atoms.

The aliphatic or cycloaliphatic carboxylic acid having 8 to 24 carbon atoms mentioned in group (I) include, for example, n-octoic acid, naphthenic acid, abietic acid, lignoceric acid and 2-ethylhexanoic acid.

(II) Methacrylic esters such as ethylene dimethacrylate, 1,3-butylene dimethacrylate, triethylolpropane trimethacrylate, and the like.

(III) Maleimides such as N,N'-m-phenylene bismaleimide, phenyl maleimide, and the like.

(IV) Oximes such as p-quinone dioxime, p,p'-dibenzoyl quinone dioxime, and the like.

In the present invention the vulcanizing agent is used in an amount of 0.01 to 20 parts by weight, preferably 0.5 to 15 parts by weight per 100 parts by weight of the rubber base. The vulcanization activator or the vulcanization accelerator is used in an amount of 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight per 100 parts by weight of the rubber base. The respective quantities of the vulcanizing agent and the vulcanization activator or the vulcanization accelerator are decided depending upon the application and the object. In general, the vulcanization velocity is somewhat accelerated with an increase in amount of these compounding agents. Further, when the vulcanizing agent and the vulcanization activator or accelerator are liquid, they can be applied as they are, or when they are solid, in the form of solutions in proper organic solvents, to the surface of an objective to be vulcanized by spraying or brushing. Accordingly, it is not always necessary to use them in admixture with the rubber base, fillers or other compounding agents.

The rubber base usable for the present invention may contain various fillers such as carbon black, talc, calcium carbonate, etc.; various higher fatty acids; coloring agents; anti-oxidants; ultraviolet absorbers; and softening agents including mineral oils.

By using the process of the present invention, there can be provided various rubber products, sheets, roofings, sealants, adhesives, paints, and the like.

Referring to Examples, the present invention is further illustrated, but should not be interpreted to be limited thereto.

EXAMPLE 1

Using chloroprene rubber as the halogen-containing amorphous polymer, examination was made on the representative vulcanization system with or without vulcanization activator or accelerator. The result thereof is shown below.

Composition

    ______________________________________                                         Chloroprene rubber 100     parts by weight                                     (Raw rubber Mooney                                                             viscosity, ML.sub.1+4 = 47(100° C.);                                    density = 1.23)                                                                SRF carbon black   50      parts by weight                                     Zinc oxide         5       parts by weight                                     Stearic acid       1       parts by weight                                     Naphthenic oil     10      parts by weight                                     Alpha-cumyl hydroper-                                                                             7       parts by weight                                     oxide (Concentration:                                                          70% by weight)                                                                 Vulcanization accelerator                                                                         2       parts by weight                                     ______________________________________                                    

Test Method

The above-mentioned materials were blended in a mixing roll and formed into a sheet with a thickness of 1 mm, which was then allowed to stand at 40° C. After a given time, the sheet was subjected to measurement of tensile strength and elongation according to JIS K-6301 (JIS is an abbreviation of Japan Industrial Standards) to examine the vulcanization state. The result obtained is as shown in Table 1.

                  TABLE 1                                                          ______________________________________                                                Vulcanization accelerator                                                                p-Quinone   Ethylene                                                 --        dioxime     dimethacrylate                                           Characteristics                                                         Vulcanization                                                                           T.sub.B  E.sub.B                                                                               T.sub.B                                                                               E.sub.B                                                                             T.sub.B                                                                               E.sub.B                            time (day)                                                                              (kg/cm.sup.2)                                                                           (%)    (kg/cm.sup.2)                                                                         (%)  (kg/cm.sup.2)                                                                         (%)                                ______________________________________                                         1        27       930    18     1120 50     730                                3        37       700    46      910 68     450                                6        36       710    71      710 77     330                                ______________________________________                                          Note:                                                                          T.sub.B : Tensile strength at break                                            E.sub.B : Elongation at break                                            

EXAMPLE 2

Examination was made on a chlorinated ethylene-propylene-diene rubber as the halogen-containing amorphous polymer. The result thereof is shown below.

Composition

    ______________________________________                                         Chlorinated ethylene-                                                                             100     parts by weight                                     propylene-diene rubber                                                         HAF carbon black   50      parts by weight                                     Zinc oxide         5       parts by weight                                     Stearic acid       1       parts by weight                                     Naphthenic oil     10      parts by weight                                     Alpha-cumyl hydroper-                                                                             7       parts by weight                                     oxide (Concentration:                                                          70% by weight)                                                                 Vulcanization accelerator                                                                         2       parts by weight                                     ______________________________________                                    

The above chlorinated ethylene-propylene-diene rubber was obtained by chlorinating an ethylene-propylene-5-ethylidene-2-norbornene rubber having a raw rubber Mooney viscosity of ML₁₊₄ =40 (100° C.), an iodine value of 12 and a propylene content of 50% by weight, to a chlorine content of 25% by weight.

Test method

The same test method as in Example 1 was repeated. The result obtained is shown in Table 2.

                  TABLE 2                                                          ______________________________________                                                                     p-Quinone                                          Vulcanization --            dioxime                                            accelerator   T.sub.B  E.sub.B  T.sub.B                                                                               E.sub.B                                 Characteristics                                                                              (Kg/cm.sup.2)                                                                           (%)      (Kg/cm.sup.2)                                                                         (%)                                     ______________________________________                                         Vulcanization                                                                           1        12       570    12     570                                   time (day)                                                                              5        18       820    24     640                                            10       30       870    45     650                                            20       65       730    135    470                                            30       103      570    165    430                                   ______________________________________                                    

EXAMPLE 3

Using chloroprene rubber, examination was made on metal oxides and metal salts of higher fatty acids as the vulcanization accelerator or activator. The result obtained is shown below.

Composition

The same as in Example 1, except that the amounts of vulcanization accelerator added are as shown in Table 3.

Test method

The same as in Example 1. The result obtained is shown in Table 3.

                                      TABLE 3                                      __________________________________________________________________________                            Chro-                                                                 Cobalt*                                                                             Iron*                                                                              mium*                                                                              Cobalt*                                                                             Magne-                                                                              Lead      Magne-                          Vulcanization naph-                                                                               naph-                                                                              naph-                                                                              abie-                                                                               sium mon-                                                                               Cobalt*(*)                                                                           sium(*)                         accelerator                                                                              --  thenate                                                                             thenate                                                                            thenate                                                                            tate oxide                                                                               oxide                                                                              abietate                                                                             oxide                           Amount (phr)                                                                             --  1    1   1   1    10   10  10    10                              __________________________________________________________________________     Character-                                                                           Vul-                                                                     istics                                                                               caniza-                                                                        tion                                                                           time                                                                           (day)                                                                    T.sub.B                                                                              1   27  105  57  44  82   44   32  9     15                              (kg/cm.sup.2)                                                                        3   37  118  72  46  103  81   47  7     21                                    5   36  100  72  50  101  91   46  8     19                                    12  38  102  76  54  110  98   61  11    20                              E.sub.B                                                                              1   930 590  860 880 780  780  850 1110  690                             (%)   3   700 420  630 630 560  580  610 1150  690                                   5   700 380  590 600 500  490  580 1000  620                                   12  550 340  390 490 400  420  490 1150  680                             __________________________________________________________________________      *Metal content: 5% by weight                                                   (*)Referential Example: alphacumyl hydroperoxide was not mixed.          

Example 3 fully proves the necessity of alphacumyl hydroperoxide as the vulcanizing agent and the effect of the oxides of these metals or the salts of these metals with higher fatty acids as the vulcanization accelerator or activator.

EXAMPLE 4

Examination was made on the effect of a vulcanization accelerator upon chloroprene at 40° C. and 70° C. The result thereof is shown below.

Test method

The same as in Example 1. The result obtained is shown in Table 4.

                                      TABLE 4                                      __________________________________________________________________________                                 Ethylene                                                                              N,N'--m-                                    Vulcanization        p-Quinone                                                                             dimetha-                                                                              phenylene                                                                             Cobalt                               accelerator   --     dioxime                                                                               crylate                                                                               bismaleimide                                                                          abietate                             __________________________________________________________________________     Compo-                                                                              Chloroprene                                                                             100    100    100    100    100                                  sition                                                                              rubber                                                                    (part by                                                                            (Raw Rubber                                                               weight)                                                                             Mooney viscosity,                                                              ML.sub.1+4 = 47                                                                (100° C.);                                                              Density = 1.23)                                                                SRF carbon black                                                                        50     50     50     50     50                                        Naphthenic oil                                                                          10     10     10     10     10                                        Zinc oxide                                                                              5      5      5      5      5                                         Stearic acid                                                                            1      1      1      1      1                                         Alpha-cumyl                                                                             7      7      7      7      7                                         hydroperoxide                                                                  Vulcanization                                                                           0      2      2      2      1                                         accelerator                                                               Vulcanization 40   70                                                                               40   70                                                                               40   70                                                                               40   70                                                                                40                                                                                70                               temperature (°C.)                                                       T.sub.B                                                                             Vulcani-                                                                             1  38  105                                                                               50  111                                                                               66  102                                                                               76  118                                                                                77                                                                               123                               (kg/cm.sup.2)                                                                       zation                                                                               3  53  114                                                                               59  134                                                                               58  110                                                                               94  130                                                                               106                                                                               128                                    time (day)                                                                           6  55  102                                                                               56  141                                                                               55  108                                                                               98  144                                                                               102                                                                               119                                          9  56  106                                                                               61  136                                                                               61  -- 87  128                                                                               110                                                                               --                                           15 58  -- 69  -- 65  -- 94  -- 108                                                                               --                                E.sub.B                                                                             Vulcani-                                                                             1  880 380                                                                               870 320                                                                               520 270                                                                               560 160                                                                               600                                                                               300                               (%)  zation                                                                               3  740 280                                                                               880 280                                                                               470 310                                                                               390 160                                                                               450                                                                               310                                    time (day)                                                                           6  650 230                                                                               850 240                                                                               440 210                                                                               230 140                                                                               430                                                                               250                                          9  680 220                                                                               810 240                                                                               400 -- 290 130                                                                               360                                                                               --                                           15 600 -- 710 -- 380 -- 240 -- 350                                                                               --                                __________________________________________________________________________

EXAMPLE 5

Examination was made on the effect of carbon black upon the low temperature vulcanization of the same chlorinated ethylene-propylene-diene rubber as in Example 2. The result thereof is given below.

Composition

    ______________________________________                                         Chlorinated-ethylene-                                                                             100    parts by weight                                      propylene-diene rubber                                                         Carbon black       50     parts by weight                                      Naphthenic oil     5      parts by weight                                      Zinc oxide         5      parts by weight                                      Stearic acid       1      parts by weight                                      Alpha-cumyl        7      parts by weight                                      hydroperoxide                                                                  p-Quinone dioxime  2      parts by weight                                      ______________________________________                                    

Test method

The same as in Example 1. The result obtained is shown in Table 5.

                  TABLE 5                                                          ______________________________________                                         Kind of carbon black                                                                            ISAF    HAF     FEF   GPF                                     ______________________________________                                         T.sub.B Vulcani-  1      13    9     11    8                                   (kg/cm.sup.2)                                                                          zation    6      15    14    13    11                                          time      20     123   111   102   68                                          (day)     30     202   149   133   105                                 E.sub.B Vulcani-  1      370   350   390   450                                 (%)     zation    6      620   650   790   760                                         time      20     480   470   520   590                                         (day)     30     330   350   400   450                                 ______________________________________                                    

EXAMPLE 6

Examination was made on mixtures of a halogen-containing amorphous polymer and the halogen-free amorphous copolymer as the rubber base, in which chloroprene rubber was used as the halogen-containing amorphous polymer and the same ethylene-propylene-diene rubber as in Example 2 was used as the halogen-free amorphous copolymer.

Test Method

The same as in Example 1. The result obtained is shown in Table 6.

                                      TABLE 6                                      __________________________________________________________________________     Composition                                                                           Chloroprene rubber                                                                             100 75  50  25  --*                                     (part by                                                                              (Raw rubber Mooney viscosity,                                           weight)                                                                               ML.sub.1+4 = 47 (100° C.);                                              density = 1.23)                                                                Ethylene-propylene-diene rubber                                                                --  25  50  75  100                                            SRF carbon black                                                                               50  50  50  50  50                                             Naphthenic oil  10  10  10  10  10                                             Zinc oxide      5   5   5   5   5                                              Stearic acid    1   1   1   1   1                                              Alpha-cumyl hydroperoxide                                                                      7   7   7   7   7                                              Cobalt abietate 0.5 0.5 0.5 0.5 0.5                                            p-Quinone dioxime                                                                              2   2   2   2   2                                       T.sub.B                                                                               Vulcanization                                                                           1      60  47  41  54  87                                      (kg/cm.sup.2)                                                                         time (day)                                                                              3      73  64  68  69  101                                                     10     87  88  93  80  102                                     E.sub.B                                                                               Vulcanization                                                                           1      780 660 510 420 340                                     (%)    time (day)                                                                              3      530 490 490 420 350                                                     10     400 420 420 340 300                                     __________________________________________________________________________      *Referential example                                                     

EXAMPLE 7

Examination was made on the effect of vulcanizing agent upon the low temperature vulcanization of chloroprene rubber as the halogen-containing amorphous polymer.

Composition

    ______________________________________                                         Chloroprene rubber  100     parts by weight                                    (Raw rubber Mooney viscosity,                                                  ML.sub.1+4 = 47 (100°);                                                 density = 1.23)                                                                SRF carbon black    50      parts by weight                                    Naphthenic oil      10      parts by weight                                    Zinc oxide          5       parts by weight                                    Stearic acid        1       parts by weight                                    Cobalt abietate     0.5     parts by weight                                    Vulcanizing agent   1/30 mole.                                                 ______________________________________                                    

Test method

The same test method as in Example 1 was repeated, except that vulcanization was carried out at room temperature.

The result obtained is shown in Table 7.

                                      TABLE 7                                      __________________________________________________________________________                           m,p-Diiso-                                                             Tertiary-                                                                              propyl  p-Menthane                                                                           Methyl ethyl                               Kind of vulca-                                                                               butyl   benzene mono-                                                                          hydro-                                                                               ketone                                     nizing agent  hydroperoxide                                                                          hydroperoxide                                                                          peroxide                                                                             peroxide                                   __________________________________________________________________________     T.sub.B                                                                             Vulcaniza-                                                                           1  35      69      61    26                                         (kg/cm.sup.2)                                                                       tion time                                                                            3  45      93      82    35                                              (day) 5  53      89      85    45                                                    7  72      101     89    48                                                    10 69      105     94    58                                         E.sub.B                                                                             Vulcani-                                                                             1  830     750     780   810                                        (%)  zation time                                                                          3  790     700     750   790                                             (day) 5  690     690     740   770                                                   7  610     600     700   730                                                   10 610     500     690   690                                        __________________________________________________________________________ 

What is claimed is:
 1. A process for vulcanizing a non-aqueous rubber base comprising at least one halogen-containing amorphous polymer other than chloroprene rubber, said process comprisingvulcanizing said non-aqueous rubber base at a temperature ranging from 5° to 85° C. in the presence of 0.01 to 20 parts by weight of at least one vulcanizing agent selected from the group consisting of an organic hydroperoxide and ketone peroxide per 100 parts by weight of said rubber, and 0.01 to 20 parts by weight of at least one vulcanization activator or accelerator selected from the group consisting of ethylene dimethacrylate, 1,3-butylene dimethacrylate, triethylolpropane trimethacrylate, p-quinone dioxime, and p,p'-dibenzoyl quinone dioxime.
 2. The process of claim 1 wherein said vulcanization activator or accelerator is ethylene dimethyacrylate.
 3. The process of claim 1 wherein said vulcanization activator or accelerator is 1,3-butylene dimethyacrylate.
 4. The process of claim 1 wherein said vulcanization activator or accelerator is triethylolpropane trimethacrylate.
 5. The process of claim 1 wherein said vulcanization activator or accelerator is p-quinone dioxime.
 6. The process of claim 1 wherein said vulcanization activator or accelerator is p,p'-dibenzoyl quinone dioxime.
 7. The process of claim 1 wherein said vulcanizing agent is present in an amount of 0.5 to 15 parts by weight.
 8. The process of claim 1 wherein said vulcanizing agent is selected from the group consisting of alpha-cumyl hydroperoxide, teriary-butyl hydroperoxide, p-menthane hydroperoxide, m,p-diisopropylbenzene monohydroperoxide, methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide, and acetylacetone peroxide.
 9. The process of claim 1 wherein said vulcanizing agent is alpha-cumyl hydroperoxide.
 10. The process of claim 1 wherein said halogen-containing amorphous polymer is a member selected from the group consisting of chlorinated polyethylene, chlorosulfonated polyethylene, and chlorinated ethylene-propylene-diene rubbers.
 11. The process of claim 1 wherein said halogen-containing amorphous polymer contains a halogen-free amorphous polymer.
 12. The process of claim 11 wherein said halogen-free amorphous polymer is a member selected from the group consisting of styrene-butadiene rubber, ethylene-propylene-diene rubbers, natural rubber, and low molecular weight ethylene-propylene rubber.
 13. Vulcanized halogen-containing amorphous polymer produced by the process of claim
 1. 